Does this patient with diabetes have large-fiber peripheral neuropathy?

Diabetic peripheral neuropathy predisposes patients to foot ulceration that heals poorly and too often leads to amputation. Large-fiber peripheral neuropathy (LFPN), one common form of diabetic neuropathy, when detected early prompts aggressive measures to prevent progression to foot ulceration and its associated morbidity and mortality.

To systematically review the literature to determine the clinical examination findings predictive of asymptomatic LFPN before foot ulceration develops.

MEDLINE (January 1966-November 2009) and EMBASE (1980-2009 [week 50]) databases were searched for articles on bedside diagnosis of diabetic peripheral neuropathy. Included studies compared elements of history or physical examination with nerve conduction testing as the reference standard.

Of 1388 articles, 9 on diagnostic accuracy and 3 on precision met inclusion criteria. The prevalence of diabetic LFPN ranged from 23% to 79%. A score greater than 4 on a symptom questionnaire developed by the Italian Society of Diabetology increases the likelihood of LFPN (likelihood ratio [LR], 4.0; 95% confidence interval [CI], 2.9-5.6; negative LR, 0.19; 95% CI, 0.10-0.38). The most useful examination findings were vibration perception with a 128-Hz tuning fork (LR range, 16-35) and pressure sensation with a 5.07 Semmes-Weinstein monofilament (LR range, 11-16). Normal results on vibration testing (LR range, 0.33-0.51) or monofilament (LR range, 0.09-0.54) make LFPN less likely. Combinations of signs did not perform better than these 2 individual findings.

Physical examination is most useful in evaluating for LFPN in patients with diabetes. Abnormal results on monofilament testing and vibratory perception (alone or in combination with the appearance of the feet, ulceration, and ankle reflexes) are the most helpful signs.